The present application relates to antifuses, and more particularly, to metal-to-metal antifuses fabricated using carbon-containing antifuse layers.
Metal-to-metal antifuses are well known in the art. These devices are formed above a semiconductor substrate, usually between two metal interconnect layers in an integrated circuit and comprises an antifuse material layer sandwiched between a pair of lower and upper conductive electrodes, each electrode in electrical contact with one of the two metal interconnect layers.
Numerous materials have been proposed for use as antifuse material layers in above-substrate antifuses. Such materials include amorphous silicon or an alloy thereof, poly silicon, crystalline carbon, silicon, germanium, chalcogenide elements.
A metal-to-metal antifuse is disposed between two metal interconnect layers in an integrated circuit. An insulating layer is disposed above a lower metal interconnect layer. The insulating layer includes a via formed therethrough containing a tungsten plug in electrical contact with the lower metal interconnect layer. The tungsten plug forms a lower electrode of the antifuse. The upper surface of the tungsten plug is planarized with the upper surface of the insulating layer. In a first embodiment, an antifuse layer comprising a material selected from the group including amorphous carbon, amorphous carbon doped with hydrogen or fluorine, and amorphous silicon carbide is disposed above the upper surface of the tungsten plug. An adhesion-promoting layer of a material such as SiN or SiC may be provided at the interfaces of the antifuse layer and the other layers in the structure. A barrier metal layer disposed over the antifuse layer forms an upper electrode of the antifuse. In a second embodiment, a barrier metal layer is also disposed between the top surface of the tungsten plug and the antifuse layer.